<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程</title>
<style>
.dropbtn {
    background-color: #4caf50;
    color: white;
    padding: 16px;
    font-size: 16px;
    border: none;
    cursor: pointer;
}
.dropdown{

    position: relative;
    display: inline-block;
}
.dropdown-content{
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0, 0,0, 2);
}
.dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
}

.dropdown-content a:hover {
    background-color: #f1f1f1;
}
.dropdown:hover .dropdown-content {
    display: block;
}
.dropdown:hover .dropbtn {
    background-color: #3e8e41;
}
</style>
</head>
<body>
    <h2>下拉菜单</h2>
    <p>鼠标移动到按钮上打开下拉菜单</p>
    <div class="dropdown">
        <button class="dropbtn">下拉菜单</button>
        <div class="dropdown-content">
            <a href="http://www.runoob.com">菜鸟教程1</a>
            <a href="http://www.runoob.com">菜鸟教程2</a>
            <a href="http://www.runoob.com">菜鸟教程3</a>
        </div>
        </div>
        </body>
</html>